A major objective in educating patients on how to deal with the disease of diabetes is to have them recognize the importance of regularly checking their blood glucose levels. Currently, blood glucose testing meters have advanced to a level requiring a very small blood sample; however, obtaining even a small sample with a lancet device still inflicts unpredictable discomfort that many patients refuse to tolerate. In reality, the initial function of all reusable lancet devices begins to degrade from the first use and gradually tissue penetration depth varies even though the depth settings on the devices remain unchanged. Many lancet device designs involve some form of elastic mechanism (e.g., a metal spring) that compresses under stress (in an engaged or a cocked position) and returns to a relaxed state when the stress is removed (decompression after release). With repeated use (compression and decompression of the elastic material) there is a gradual change from the initial elasticity design of the drive mechanism. This change may adversely affect the functional design parameters of a lancet device and result in inconsistent lancet tissue penetration depth. Depth settings may become unreliable and deviations in the speed of entry and withdrawal of lancets into tissue may occur. Such changes may lead directly to user discomfort. A newly diagnosed diabetic patient may initially find blood glucose testing acceptable but later discover that the depth setting on his lancet device (e.g., a setting of level 4 on a 1 through 9 depth scale) suddenly or gradually changes to a greater or lesser tissue penetration depth. Patients often attempt to offset these changes by adjusting their lancet devices to compensate for this unexpected development. Once the patients determine a new acceptable depth setting, which frequently involves pain resulting from trial and error, the elasticity of the drive mechanism may again change. Understandably, this scenario results in patient frustration and reluctance to continue glucose testing.
Drive mechanisms employing magnetic forces have been developed. For example, electromagnet drive mechanisms have been developed but may be impractical for home or away-from-home glucose testing. In addition, U.S. Patent Application Publication No. 2005/0125019 to Kudrna et al. discloses a lancet device comprising an internal magnet for driving and retracting a lancet. An outer sleeve is attached to a collar, while the magnet and lancet are secured to an inner sleeve. The inner sleeve is capable of moving longitudinally within the outer sleeve. Kudrna also discloses an arming member for moving the lancet, collar, and inner and outer sleeves to an armed position. A button switch activates the device such that the attractive force between the magnet and the collar propels the lancet forward to a piercing position. In addition, Kudrna discloses that the attractive force between the magnet and the collar acts to retract the lancet to a steady-state position.
Despite these improvements in lancet devices, it would be advantageous to provide a lancet device that provides reliable and consistent depth penetration. Moreover, it would be advantageous to provide a lancet device that is easily manufactured and user friendly. In addition, it would be advantageous to provide a lancet device that is inexpensive and of simple construction.